Rainfall

Rainfall in June 2011 was near average for most of sites, with monthly rainfall
totals across the metropolitan area generally in the 100-200 mm range.

A strong cold front produced moderate to heavy rainfall at the start of June,
with daily rainfall totals of 20 to 40 mm recorded in the 24 hours to 9 am on
the 2nd on the mainland. Some damage was reported in Perth, mainly due to flash
flooding. After a lengthy break, a series of cold fronts passed through the
Perth area in the second half of June bringing much anticipated rainfall. The
most significant falls occurred in the late afternoon of the 24th through to
the early morning of the 25th, with many sites registering daily rainfall totals
in the 50 to 60 mm range. As a result, flash flooding caused some property damage.
Swanbourne recorded 32.6 mm in 30 minutes (between 1745 WST and 1814 WST) on
the 24th, which equates to a 1 in 50 to 1 in 100 year event, whilst Swanbourne's
24 hour rainfall total of 63.8 mm to 9 am on the 25th exceeded the previous
highest daily total for June in 18 years of record, which was 53.0 mm on 4 June
2002.

Perth Metro recorded 171.4 mm of rainfall on 14 days during June 2011, which
is the wettest June for 6 years since 251.0 mm was recorded on 19 rain days
in 2005. Despite this, the total rainfall for the six months from January to
June 2011 at Perth Metro was still below average, with 306.4 mm recorded on
35 rain days. The long-term average for this period is 379.0 mm on about 42
days, while the total for the same period last year was 205.6 mm on 23 days.

Maximum temperature

Daytime temperatures during June 2011 were near average across the Perth metropolitan
area. Mean daily maximum temperatures were in the 19 to 20 °C range for
most sites, and generally less than 1 °C above normal. The warmest day of
the month was the 27th, with daily maximum temperatures in low to mid 20s, as
Gosnells City recorded
the highest daily maximum in the Perth metropolitan area for June 2011 with
24.8 °C.

Perth Metro's mean maximum temperature in June 2011 was 19.5°C, which is
near the average of 19.3 °C. Daily maxima ranged from a cool 14.2 °C
on the 14th, which was Perth Metro's coolest June day since 12.8 °C was
recorded on 23 June 2009, to 24.3 °C on the 27th.

Perth Metro's mean maximum temperature for the 6 months (January to June )
period was 28.1 °C, which is the warmest January to June period since records
commenced in Perth in 1897. The previous record for the same period was 27.6
°C in 1978, whilst the average is 26.5 °C.

Minimum temperature

Overnight temperatures during June 2011 were above average across the Perth
area. Mean daily minimum temperatures were in the 9 to 14 °C range, and
generally 1 to 2 °C above normal. The coldest night of the month for many
sites was on the 6th, with several sites registering daily minima temperatures
5 °C or lower, and Jandakot Aerodrome recorded the lowest minimum in Perth
in June 2011 with 1.3°C.

Perth Metro's mean minimum temperature in June was 10.0 °C, which is above
the average of 8.5 °C, and the warmest June for 7 years, since 10.6 °C
was recorded in 2004. Minima at Perth Metro ranged from a cold 3.3 °C on
the 6th, to a mild 15.0 °C on the 20th, the highest overnight minimum for
June at Perth Metro in three years, since 15.1 °C was recorded on 1 June
2008.

Wind and sunshine

Severe wind gusts were observed at Rottnest Island in the early morning on
the 14th as a maximum wind gust of 91 km/h was observed at 0653 WST when a cold
front crossed the Perth region. The was the strongest wind gust reported in
the region in June 2011.

Perth recorded an average daily sunshine of 5.6 hours in June 2011, which is
the least sunshine hours for Perth in June for 6 years, since 4.8 hours per
day was recorded in 2005. The average sunshine for Perth in June is 6.0 hours
per day.

Most values are the precipitation in the 24 hours to 9 am on the day indicated.
Days marked with »» are part of a longer accumulation, which is marked like this on the final day.
Values over 100 mm have been rounded to the nearest whole millimetre.
Days marked with - have a rainfall report of zero;
days left blank have no rainfall report (which often indicates no rain fell).
This table is very wide; you may have to scroll sideways to see all the days, and you may need to set the paper to 'landscape' to print.

Notes

This statement was prepared before all data for the period were available. This may affect some of the statistics presented.

A Monthly Climate Summary is prepared to list the main features of the weather in Perth using the most timely and accurate information available on the date of publication; it will generally not be updated. Later information, including data that has had greater opportunity for quality control, will be presented in the Monthly Weather Review, usually published in the fourth week of the month.

This statement has been prepared based on information available at
12 pm on Thursday 30 June 2011.
Some checks have been made on the data, but it is possible that results will change
as new information becomes available.

Averages are long-term means based on observations from all available
years of record, which vary widely from site to site. They are not shown for
sites with less than 10 years of record.
The median
is sometimes more representative than the
mean
of long-term average rain.

The Rank indicates how rainfall this time compares with the climate record for the site,
based on the
decile ranking
(very low rainfall is in decile 1, low in decile 2 or 3,
average in decile 4 to 7, high in decile 8 or 9
and very high is in decile 10).
The Fraction of average shows how much rain has fallen this time as a
percentage of the long-term mean.

Records in this summary are based on sites with at least 10 years of data.

*Official Perth observations have been recorded at several different sites
with varying instrumentation over the years, and these changes can affect
the continuity of the climate record. For the current Mt Lawley site, the
most significant changes of this kind relate to minimum temperature and rain
days.

For that reason, current mean temperature and rain-day data quoted here are
based only on readings from the Mt Lawley site, which commenced observations
in 1993. Sunshine recordings are from Perth Airport and for similar reasons
current means use only Perth Airport data, which commenced in 1993.

For PDF files of Perth Metro climate statistics for other months,
please click here
for extremes and here
for averages.